BS EN 1092-1 is a comprehensive European standard for circular steel flanges used in industrial piping systems. It establishes strict requirements for flange types, facings, dimensions, tolerances, and materials, ensuring dimensional consistency and compatibility across components from different suppliers.
The standard covers PN designations from PN 2.5 to PN 400 and nominal sizes from DN 10 to DN 4000. However, PN (Nominal Pressure) does not represent a fixed maximum working pressure; allowable pressure varies depending on the material and operating temperature.
What Are BS EN 1092-1 Flanges?
BS EN 1092‑1 flanges are standardized steel flanges for bolted pipe connections. They allow pipes, valves, and equipment to be connected, disconnected, and maintained easily. The current standard is BS EN 1092‑1:2018.
How Flanged Connections Work
| Component | Function |
|---|---|
| Two mating flanges | Connect to pipes or equipment |
| Gasket | Seals between flange faces |
| Bolts / studs + nuts | Tighten to compress the gasket and create a seal |
Common Flange Types – Quick Overview
| Flange Type | Description | Best For |
|---|---|---|
| Plate | Simple, flat design | General industrial piping |
| Weld Neck | Extended hub – welded to pipe | High stress, demanding conditions |
| Slip‑On | Slides over pipe – welded | Straightforward installation |
| Blind | No bore – closes pipe end | Isolation, closure |
| Threaded | Internal threads – screws onto pipe | Where welding is not practical |
| Loose / Lapped | Used with collars – easy alignment | Frequent disassembly |
Key Specifications – Quick Overview
| Specification | Range / Options | Why It Matters |
|---|---|---|
| DN size | DN 10 to DN 4000 | Matches pipe diameter |
| PN designation | PN 2.5 to PN 400 | Pressure rating (temperature‑dependent) |
| Flange type | Plate, Weld Neck, Slip‑On, etc. | Application and strength |
| Material | Carbon steel, stainless, alloy | Medium + environment compatibility |
| Facing | Raised face, flat face, etc. | Sealing surface |
| Bolt pattern | Number and size of bolt holes | Must match mating flange |
Flange Types – Detailed Comparison
| Type | Welding Required | Strength | Maintenance Access |
|---|---|---|---|
| Plate | Yes (or threaded) | Moderate | Easy |
| Weld Neck | Yes | High | Easy |
| Slip‑On | Yes | Moderate | Easy |
| Blind | No (bolted) | N/A | Easy |
| Threaded | No | Moderate | Easy |
| Loose | No (with collar) | Moderate | Very easy |
PN Rating – Important Note
| PN Designation | Meaning |
|---|---|
| PN 2.5 to PN 400 | Pressure rating – but NOT a fixed maximum pressure |
| Actual working pressure | Depends on material + temperature |
Selection Checklist
| Factor to Check | Why It Matters |
|---|---|
| DN size | Must match pipe OD |
| PN rating | Must suit system pressure (at operating temp) |
| Flange type | Weld Neck, Slip‑On, Blind, etc. |
| Material | Compatible with medium and environment |
| Facing type | Raised face, flat face, etc. – affects sealing |
| Bolt pattern | Must match mating flange |
| Gasket material | Compatible with medium and temperature |
| Standard version | BS EN 1092‑1:2018 (current) |
Advantages of Standardized Flanges
| Advantage | Benefit |
|---|---|
| Interchangeability | Connect components from different suppliers |
| Removable | Easy inspection, maintenance, and replacement |
| Standardized dimensions | Consistent bolt patterns and facings |
| Wide availability | Common in industrial piping |
BS EN 1092-1 Key Requirements and Classifications
BS EN 1092‑1:2018 is the European standard for circular steel flanges used with pipes, valves, and fittings. It covers PN ratings, flange types, materials, dimensions, facings, bolting, and pressure/temperature ratings.
Quick Overview – Key Requirements
| Requirement Area | What It Covers |
|---|---|
| PN pressure designation | PN 2.5 to PN 400 |
| Flange types & facings | Plate, Weld Neck, Slip‑On, Blind, Threaded, Loose |
| Dimensions & tolerances | DN 10 to DN 4000 – OD, bolt circle, thickness, bore |
| Material requirements | Carbon steel, stainless, alloy – per service conditions |
| Bolting & surface finish | Bolt sizes, threading, facing finish |
| Marking & inspection | Traceability, dimensional checks, test reports |
PN Designations – Common Values
| PN Class | Typical Application |
|---|---|
| PN 6 / 10 / 16 | Low‑pressure water, air, general services |
| PN 25 / 40 | Medium‑pressure systems |
| PN 63 / 100 | Higher‑pressure industrial applications |
| PN 160 / 250 / 400 | High-pressure/demanding services |
Flange Types – Quick Reference
| Type | Description | Best For |
|---|---|---|
| Plate | Simple flat design | General low‑pressure piping |
| Weld Neck | Extended hub – welded to pipe | High stress, critical systems |
| Slip‑On | Slides over pipe – welded | Easy installation |
| Blind | No bore – closes pipe end | Isolation, closures |
| Threaded | Internal threads – screws on | No welding required |
| Loose / Lapped | With collar – easy alignment | Frequent disassembly |
Key Dimensions – Always Check
| Dimension | Why It Matters |
|---|---|
| Outside flange diameter | Matches mating flange |
| Bolt‑hole circle diameter | Alignment with counter‑flange |
| Number & size of bolt holes | Bolting compatibility |
| Flange thickness | Pressure rating & strength |
| Bore diameter | Matches pipe ID |
| Hub / welding‑end dimensions | Weld fit‑up and strength |
Material Groups – Quick Guide
| Material Type | Typical Use |
|---|---|
| Carbon steel | General industrial, water, air |
| Alloy steel | Higher temperature, higher strength |
| Stainless steel | Corrosive media, food, chemical |
| Duplex/super duplex | High corrosion + high strength |
Facing Types – Sealing Surface
| Facing Type | Description | Common Gasket |
|---|---|---|
| Raised Face (RF) | Raised sealing surface | Flat or spiral wound gasket |
| Flat Face (FF) | Flat surface – full face gasket | Full face gasket |
| Ring‑Type Joint (RTJ) | Groove for metal ring | Metal ring gasket |
Inspection & Documentation
| Requirement | Typical Deliverable |
|---|---|
| Dimensional inspection | Report confirming tolerances |
| Material test certificate | EN 10204 3.1 or 3.2 |
| Visual inspection | Surface finish and marking |
| NDT (if required) | UT, MT, PT per specification |
Selection Checklist
| Factor | Check |
|---|---|
| PN rating | ☐ Matches pressure + temp |
| Flange type | ☐ Correct for application |
| DN size | ☐ Matches pipe diameter |
| Material grade | ☐ Compatible with medium |
| Facing type | ☐ Matches gasket and mating flange |
| Bolt pattern | ☐ Aligns with counter‑flange |
| Surface finish | ☐ Suitable for gasket type |
| Marking | ☐ Traceability and standard compliance |
| Certificates | ☐ EN 10204 3.1 / 3.2 if required |
How to Choose the Right BS EN 1092-1 Flange
Choosing the right flange is about more than pipe size. You must match type, DN, PN, material, facing, bolting, pressure, temperature, and gasket to your system.
Selection Steps – Quick Overview
| Step | Factor to Check |
|---|---|
| 1 | Pipe size (DN) – match bore and OD |
| 2 | Flange type – Weld Neck, Slip‑On, Blind, etc. |
| 3 | PN designation – pressure rating (temp‑dependent) |
| 4 | Material grade – compatible with medium and environment |
| 5 | Facing type – Raised Face, Flat Face, RTJ |
| 6 | Bolt‑hole dimensions – pattern, size, count |
| 7 | Operating conditions – pressure, temp, medium, corrosion |
Step‑by‑Step Selection Table
| Step | What to Check | Why It Matters |
|---|---|---|
| 1. Pipe size | DN (10–4000) + actual OD + wall thickness | Must fit pipe correctly |
| 2. Flange type | Weld Neck, Slip‑On, Plate, Blind, Threaded, Loose | Suits installation and service |
| 3. PN rating | PN 2.5 to PN 400 – but temp‑dependent | Pressure capability – check rating table |
| 4. Material | Carbon steel, stainless, alloy, duplex | Corrosion + temperature resistance |
| 5. Facing | RF, FF, RTJ | Sealing surface – must match gasket |
| 6. Bolt pattern | Bolt circle, hole count, hole size, bolt size | Must match mating flange |
| 7. Conditions | Pressure, temp, medium, environment | Ensures safe, reliable service |
Flange Type Selection – Quick Guide
| Type | Best For | Key Feature |
|---|---|---|
| Weld Neck | High stress, critical systems | Strong, good stress distribution |
| Slip‑On | General installation | Easy to position and weld |
| Plate | Low‑pressure, general use | Simple, cost‑effective |
| Blind | Closing pipe ends | Isolation, maintenance access |
| Threaded | No welding allowed | Screws onto pipe |
| Loose / Lapped | Frequent disassembly | Easy alignment |
PN Rating – Important Note
| PN Designation | Common Use | Caution |
|---|---|---|
| PN 6, 10, 16 | Low‑pressure water, air, general | Actual pressure depends on material + temp |
| PN 25, 40 | Medium‑pressure systems | Always check rating table |
| PN 63, 100, 160+ | High‑pressure applications | PN ≠ fixed max pressure |
Material Selection Guide
| Material Group | Typical Application |
|---|---|
| Carbon steel | Water, air, general industrial |
| Alloy steel | Higher temperature, higher strength |
| Stainless steel | Corrosive media, food, chemical |
| Duplex/super duplex | High corrosion + high strength |
Facing & Gasket – Quick Reference
| Facing Type | Description | Common Gasket |
|---|---|---|
| Raised Face (RF) | Raised sealing surface | Flat, spiral wound |
| Flat Face (FF) | Full face contact | Full face gasket |
| Ring‑Type Joint (RTJ) | Groove for metal ring | Metal ring gasket |
Bolt‑Hole Compatibility Check
| Dimension | Check |
|---|---|
| Bolt‑hole circle diameter | Must match mating flange |
| Number of bolt holes | Must match |
| Hole diameter | Must fit bolt size |
| Bolt size/threading | Must match nuts and tightening tools |
Selection Checklist
| Factor | Confirmed? |
|---|---|
| DN size matches pipe | ☐ |
| Flange type selected | ☐ |
| PN rating suits pressure + temp | ☐ |
| Material compatible with medium | ☐ |
| Facing type matches gasket | ☐ |
| Bolt pattern matches mating flange | ☐ |
| Operating conditions reviewed | ☐ |
| Certificates/inspection required | ☐ |
Our BS EN 1092-1 Flange Product Recommendations and Shipping Information
We supply premium BS EN 1092-1 flanges, including Weld Neck, Slip-On, Blind, Plate, and Threaded types, engineered for industrial piping systems from DN 10 to DN 4000 and PN 2.5 to PN 400. Our flanges are manufactured to exact material grades, facing types, and dimensional specifications, ensuring reliable, leak-free connections for oil and gas, petrochemical, and general industrial applications.
We focus on dimensional consistency, material quality, and full product traceability, providing comprehensive technical documents and inspection records to support your project requirements. Custom configurations, including bore sizes, bolt-hole patterns, and surface finishes, are available to match your specific pressure, temperature, and working medium conditions.
We also offer domestic and international shipping via express, air freight, or sea freight, with flexible delivery options to meet your project timeline. To receive a customized product and shipping quotation, please contact us with your flange type, DN size, PN designation, material grade, facing type, quantity, and delivery destination. Our expert team will recommend the optimal BS EN 1092-1 flange configuration tailored to your application’s exact requirements.
Common Mistakes When Selecting BS EN 1092-1 Flanges
Selecting BS EN 1092-1 flanges requires more than just matching the nominal pipe size (DN). A common mistake is assuming the PN (Nominal Pressure) rating represents a universal maximum working pressure, when in fact, allowable pressure varies depending on the material and operating temperature.
To prevent leaks and system failures, buyers must evaluate the complete application. Key considerations include selecting the correct flange type, ensuring material compatibility with the working medium, and verifying that the flange facing matches the gasket. Additionally, confirming the exact bolt-hole pattern is essential to guarantee proper assembly, especially when connecting to equipment or valves.
Conclusion:
BS EN 1092-1 flanges are essential for creating reliable, standardized bolted connections in industrial piping systems. However, proper selection requires evaluating the complete application rather than just the nominal pipe size (DN).
FAQ：
1. What is BS EN 1092-1?
BS EN 1092-1 is a European standard for circular steel flanges used with pipes, valves, fittings, and other piping equipment. It specifies requirements for dimensions, materials, facings, PN designations, and other flange characteristics.
2. What is the difference between PN16 and PN25 flanges?
PN16 and PN25 are different nominal pressure designations. PN25 generally represents a higher pressure class than PN16, but the actual allowable working pressure also depends on the flange material and operating temperature.
3. What types of flanges are covered by BS EN 1092-1?
Common types include plate, weld neck, slip-on, blind, threaded, and loose/lap-joint flanges, depending on the applicable requirements.
4. How do I choose the right BS EN 1092-1 flange?
Consider the DN size, flange type, PN designation, material, facing, bolt pattern, pressure, temperature, gasket, and working medium. These factors should be checked together to ensure compatibility and reliable performance.
Post time: Aug-24-2026